The flow rate of refrigerant R-12 in a refrigerator is 0.03 kg/s. The refrigerant enters the compressor as saturated at 150.9 kPa. After adiabatic compression, it entres the condenser as superheated vapour at 500 kPa and 1OO ºC and leaves the condenser as a saturated liquid at the same pressure.

Pressure

Temperature

Specific enthalpy

(kpa)

(ºC)

Hr
(KJ/KG)

hg
(KJ/KG)

150.9

-20

17.82

178.74

500

15.6

50.64

195.01

For the saturated vapour at 500 kPa and 100ºC, h = 252.05 kJ/kg.

Using the data given above, the refrigeration effect in kW will be:

Question

Pressure	Temperature	Specific enthalpy
(kpa)	(ºC)	Hr (KJ/KG)	hg (KJ/KG)
150.9	-20	17.82	178.74
500	15.6	50.64	195.01
For the saturated vapour at 500 kPa and 100ºC, h = 252.05 kJ/kg.